• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.8-16
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• 2018

Purpose: The purpose of this study is to evaluate the accuracy of surgical stent according to the supported type. Materials and methods: 5 sets of dental models which have tooth supported edentulous area and tooth-tissue supported edentulous area were made. Dental model were scanned with model scanner, and CBCT was taken. CT data and model scan data were overlapped using In2Guide software, implant were virtually planned in the software. Surgical stents are fabricated by 3D printing. The implant fixture were installed using the surgical stent, CBCT were retaken. CBCT before surgery and after surgery were overlapped, and the differences (angle difference, coronal difference, apical difference) were evaluated using statistical analysis. Results: In the assessment of the accuracy of surgical guides according to arch type, there are no statistically significant differences between maxilla and mandible. In the case of support type, tooth supported stents showed lower angle difference and length difference than tooth-tissue supported stents, which are statistically significant. Conclusion: Arch type does not affect the accuracy of surgical stents. But tooth support stents are more accurate than tooth-tissue support stents in the case of angle and length difference.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.227-237
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• 2008

STATEMENT OF PROBLEM: Zirconium oxide can be a substitute to titanium as implant materials to solve the esthetic problems of dark color in the gingival portion of implant restorations. PURPOSE: This study was performed to define attachment and growth behavior of osteoblast- like cells cultured on grooved surfaces of zirconium oxide and evaluate the genetic effect of zirconium oxide surfaces using the reverse transcriptase-polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: MC3T3-E1 cells were cultured on (1) commercially pure titanium discs with smooth surface (T group), (2) yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with machined surface (ZS group), and (3) Y-TZP with $100{\mu}m$ grooves (ZG group). Cell proliferation activity was evaluated through MTT assay and cell morphology was examined by SEM. The mRNA expression of Runx2, alkaline phosphatase, osteocalcin, TGF-${\beta}1$, IGF-1, G3PDH in E1 cells were evaluated by RT-PCR. RESULTS: From the MTT assay, after 48 hours of adhesion of MC3T3-E1 cells, the mean optical density value of T group and ZG group significantly increased compared to the ZS group. SEM images of osteoblast-like cells showed that significantly more cells were observed to attach to the grooves and appeared to follow the direction of the grooves. After 24 hours of cell adhesion, more spreading and flattening of cells with active filopodia formation occurred. Results of RT-PCR suggest that T group, ZS group, and ZG group showed comparable osteoblast-specific gene expression after 24 hours of cell incubation. CONCLUSION: Surface topography and material of implants can play an important role in expression of osteoblast phenotype markers. Zirconia ceramic showed comparable biological responses of osteoblast-like cells with titanium during a short-time cell culture period. Also, grooves influence cell spreading and guide the cells to be aligned within surface grooves.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.1
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• pp.30-36
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• 2015

Objectives: The aim of this study is to determine the incidence, location, and orientation of maxillary sinus septa in formalin embalmed cadavers. Materials and Methods: The study was conducted on 210 cadaveric heads available in our department. After taking the mid-sagittal section the specimens were opened from the medial aspect and the sinus sinus septa, their anatomical plane, location and dimensions. Results: The mean linear distance between maxillary sinus floor and its anatomical ostium was $26.76{\pm}5.21mm$ and $26.91{\pm}4.96mm$ on right and left side, respectively. A total of 59 maxillary sinus septa (28.1%) were observed in 210 maxillary specimens. Septae were most common, 33 septa (55.9%), in the middle region (between first and second molar tooth) of the sinus cavity. The maxillary sinus membrane (Schneiderian membrane) adhered tightly to the maxillary sinus and over the septae. Significantly more maxillary sinus septa were observed in edentulous maxillae in comparison to the dentate upper jaw. Conclusion: Knowledge of location of maxillary sinus ostium is mandatory for the rhinologist for drainage of secretions in maxillary sinusitis. The morphological details of maxillary sinus septa, particularly their location and anatomical planes, will guide dentists in performance of safe implant surgeries. The maxillary antrum septa of category I and II may complicate the procedure of inversion of bone plate and elevation of sinus membrane during maxillary augmentation surgeries. The category III septa observed in the sagittal plane were embedded by one of the branches of the infraorbital nerve in it, and if accidentally cut will lead to infraorbital nerve palsy in maxillary sinus surgeries.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.2
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• pp.158-168
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• 2015

This article describes how to use digital system in a fully edentulous case that diagnosis to definitive prosthesis fabrication. While proceeding oral scan and CBCT taking, digital markers were attached on maxillary palate and lower existing denture. Using CBCT image and oral scan image, the bone contour and anatomical structures were analyzed and flapless surgical guide, customized abutment and prosthesis were made. After the osseointegration, the definitive prosthesis was fabricated using the oral scan image with scan body. It provides clinicians with a fast workflow and improves clinical efficiency.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.38-40
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• 2005

Microdrive with high precision and light mass enough to install on mouse head was fabricated for recording the reliable signal of neuron cell to understand the brain study. The proposed microdrive has three H-form PZT actuators and its guide structure. The microdrive operation principle is based on the well known inchworm principle. The synchronization of three PZT actuators is able to produce the linear motion along the guide structure. Our proposed microdrive has a precise accuracy of about 100nm and a long stroke of about 5mm. The electrode which is used for the recording of the action potential of the neuron cell was fixed at one of PZT actuators. The proposed microdrive was suited to acquisition of signals from in vivo extra-cellular single-unit recoding. On the condition of the anesthetized mouse, the single-unit signals could be recorded by using the proposed microdrive. In addition, applying the PZT microdrive to an alert mouse, we try to implant it on a mouse brain skull to explore single neuron firing.

• Clinics in Shoulder and Elbow
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• v.22 no.1
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• pp.16-23
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• 2019

Background: We aimed to evaluate whether the use of our novel patient-specific guide (PSG) with 3-dimensional reconstruction in reverse total shoulder arthroplasty (RTSA) would allow accurate and reliable implantation of the glenoid and humeral components. Methods: 20 fresh-frozen cadaveric shoulders were used. The PSG group (n=10) and conventional group (n=10) was evaluated the accuracy and reproducibility of implant positioning between before and after surgery on the computed tomography image. Results: The superoinferior and anteroposterior offset in the glenoid component were $0.42{\pm}0.07$, $0.50{\pm}0.08$ in the conventional group and $0.45{\pm}0.03$, $0.46{\pm}0.02$ in the PSG group. The inclination and version angles were $-1.93^{\circ}{\pm}4.31^{\circ}$, $2.27^{\circ}{\pm}5.91^{\circ}$ and $0.46^{\circ}{\pm}0.02^{\circ}$, $3.38^{\circ}{\pm}2.79^{\circ}$. The standard deviation showed a smaller difference in the PSG group. The anteroposterior and lateromedial humeral canal center offset in the humeral component were $0.45{\pm}0.12$, $0.48{\pm}0.15$ in the conventional group and $0.46{\pm}0.59$ (p=0.794), $0.46{\pm}0.06$ (p=0.702) in the PSG group. The PSG showed significantly better humeral stem alignment. Conclusions: The use of PSGs with 3-dimensional reconstruction reduces variabilities in glenoid and humerus component positions and prevents extreme positioning errors in RTSA.

• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.435-441
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• 2002

Surgical microscrews were introduced and used as one method to provide absolute anchorage. Some clinicians implanted microscrews or miniscrews into the basal bone below the roots of the teeth to evade damage to the roots. Because the implanted microscrews were positioned too low the applied force was insufficient to retract the anterior teeth or protract the posterior teeth, and the use of microscrews or miniscrews seemed limited in applying vertical force. However Park implanted microscrews(micro-implants (1.2mm in diameter)) into the alveolar bone between the roots of the posterior teeth to change the direction of the applied force toward increasing horizontal component of the force. Moreover, these microscrew implants were positioned in the alveolar bone between the roots without causing discernable damage to the roots. This study was performed to provide guidelines and anatomic data to assist in the determination of the safe location for micro-implants. By measuring the CT images from 21 patients, anatomical data were obtained which were then used as a guide to determine the location for the implantation of micro-implants. The thickness of the cortical bones at the alveaolar bone region increased from the anterior to the posterior teeth area. The mandibular posterior teeth area showed thicker cortical bone. A greater distance was observed in distance between the second premolar root and first molar root in the upper arch, between the first molar root and the second molar root in the lower arch. The alveolar bone of the posterior teeth area is considered the best site for the implantation of micro-implants.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.33.1-33.7
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• 2019

Background: The concept of the ideal morphology for the alveolar bone form is an important element to reconstruct or restore the in maximizing esthetic profile and functional alveolar bone restoration. The purpose of this preliminary study is to evaluate the normal alveolar bone structure to provide the standard reference and guide template for use in diagnosing for implant placement, determining the correct amount of bone augmentation in actual clinical practice and producing prostheses based on three-dimensional imaging assessment of alveolar bone. Methods: This study was included 11 men and 11 women (average age, 22.6 and 24.5 years, respectively) selected from among 127 patients. The horizontal widths of alveolar bone of maxilla and mandible were measured at the crestal, mid-root, and root apex level on MDCT (multi-detector computed tomography) images reconstructed by medical imaging software. In addition, tooth dimensions of the central incisors, canines, second premolars, and first molars of maxilla and mandible, including the horizontal width of the interdental alveolar bone crest, were also measured and statistically analyzed. Results: The horizontal alveolar bone width of the palatal side of maxilla showed a distinct increment from the alveolar bone crest to the apical region in both anterior and posterior areas. The average widths of the maxillary alveolar ridge were as follows: central incisor, 7.43 mm; canine, 8.91 mm; second premolar, 9.57 mm; and first molar, 12.38 mm. The average widths of the mandibular alveolar ridge were as follows: central incisor, 6.21 mm; canine, 8.55 mm; second premolar, 8.45 mm; and first molar, 10.02 mm. In the buccal side, the alveolar bone width was not increased from the crest to the apical region. The horizontal alveolar bone width of an apical and mandibular border region was thinner than at the mid-root level. Conclusions: The results of the preliminary study are useful as a clinical guideline when determining dental implant diameter and position. And also, these measurements can also be useful during the production of prefabricated membranes and customized alveolar bone scaffolds.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.139-146
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• 2012

Purpose: An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods: A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results: The deviation of the entry point and angulation of the central axis in the reference plane were $0.47{\pm}0.27$ mm, $0.57{\pm}0.23$ mm, and $0.64{\pm}0.16^{\circ}$, $0.57{\pm}0.15^{\circ}$, respectively. However, for the two different angulations in each group, the $20^{\circ}$ angulation showed a greater error in the deviation of the entry point than did the $10^{\circ}$ angulation. Conclusion: The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.362-373
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• 2022

For a full-mouth fixed prosthetic treatment of the edentulous patient, it is essential to confirm the proper tooth position and thorough evaluation of the remaining alveolar bone and soft tissue before surgery. CAD-CAM dentistry and guided implant surgery have such advantages of providing simultaneous planning of surgery and prosthetic treatment to ensure pre-knowledge of the treatment. In this clinical case, using the digital technology, digital temporary denture fabrication, esthetic evaluation before fixed prostheses treatment, and guided surgery planning was possible. After the surgery, previously obtained data was used for fabricating fixed temporary prostheses. Definitive zirconia prostheses transferred from the provisional prostheses were fabricated and functionally and esthetically satisfying results were obtained.